Most people also don't ride roller coasters. Anything that's only open to the healthiest part of the adult population will be a fringe mode of transport.

Just look at bicycling: If there are flat routes away from most car traffic that link residential to commercial districts, the entire family will go out on bicycles for everyday errands, and the roads will be full of bicyclists. But if the only route between home and errand is a multi-lane stroad where any pedestrian or bicyclist takes their life in their own hand? Expect to only see a young single man occasionally.